drm/rockchip: add drm summary debugfs node

drm/rockchip: add drm summary debugfs node

With the summary debug node, show current display status would be easier.

Using step:
shell# cat /sys/kernel/debug/dri/0/summary

vop name: ff900000.vop status=active
Display mode: 1200x1920 fps[60] clk[160000] type[8] flag[a]
        H: 1200 1320 1340 1361
        V: 1920 1941 1944 1962
win0-0: status=active
        format: AB24 little-endian (0x34324241)
        zpos: 0
        src: pos[0x0] rect[1200x1920]
        dst: pos[0x0] rect[1200x1920]
        buf[0]: addr: 0x9e19000 pitch: 4800 offset: 0
win1-0: status=disabled
win2-0: status=disabled
win2-0: status=disabled
win2-1: status=disabled
win2-2: status=disabled
win3-0: status=disabled
win3-0: status=disabled
win3-1: status=disabled
win3-2: status=disabled
vop name: ff8f0000.vop status=disabled

Change-Id: I386398b0617f0c18902c4cadad5906be343cc4de
Signed-off-by: Mark Yao <mark.yao@rock-chips.com>